Method and apparatus for synchronization in an ofdma evolved utra wireless communication system

ABSTRACT

A method and apparatus for synchronization in an orthogonal frequency division multiple access (OFDMA) evolved universal terrestrial radio access (E-UTRA) system including at least one base station and a plurality of wireless transmit/receive units (WTRUs). A secondary synchronization channel (S-SCH) symbol is generated to include cell-specific information. The S-SCH symbol is mapped to the center of the available bandwidth of the system. In one embodiment, the S-SCH symbol is transmitted on different subcarriers at different sectors in the system. In another embodiment, the S-SCH symbol is transmitted on the same subcarriers at different sectors in the system.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/792,774, filed Apr. 18, 2006, which is incorporated herein byreference as if fully set forth.

FIELD OF INVENTION

The present invention is related to synchronization in wirelesscommunication systems. More particularly, the present invention isrelated to a method and apparatus for synchronization in an orthogonalfrequency division multiple access (OFDMA) evolved universal terrestrialradio access (E-UTRA) system.

BACKGROUND

Both the Third Generation Partnership Project (3GPP) and 3GPP2, in orderto keep the technology competitive for a longer time period, areconsidering long term evolution. Accordingly, evolution of radiointerfaces and network architecture is necessary to support this goal.

Currently, orthogonal frequency division multiple access (OFDMA) isbeing considered for the downlink of evolved universal terrestrial radioaccess (E-UTRA). In the current state of the art, when a user equipment(UE) powers on in the E-UTRA system having an OFDMA based downlink, itsynchronizes frequency, downlink frame timing and the Fast FourierTransform (FFT) symbol timing with the best cell. In addition, the UEidentifies the cell ID. This collective process may be referred to asthe “cell search.”

The synchronization channel and cell search process for OFDMA-baseddownlink are currently being studied in E-UTRA. It would be desirable todefine a synchronization channel that is a common for all cells in thesystem. In one regard, it has been determined that that downlinksynchronization channel (SCH) is transmitted using 1.25 MHz or 5 MHzbandwidth regardless of the entire bandwidth of the system. In this way,the same SCH is mapped to the central part of transmission bandwidth.

Given the differences between universal mobile telecommunications system(UMTS) UTRA and evolved UTRA, it would be desirable to provide a newsecondary SCH (S-SCH) for evolved UTRA.

SUMMARY

The present invention is related to a method and apparatus forsynchronization in an OFDMA E-UTRA system including at least one basestation and a plurality of wireless transmit/receive units (WTRUs). Themethod comprises configuring a secondary synchronization channel (S-SCH)symbol to include cell-specific information. The S-SCH is mapped to acentral bandwidth of the system. In one embodiment, the S-SCH symbol istransmitted on different subcarriers at different sectors in the system.In another embodiment, the S-SCH symbol is transmitted on the samesubcarriers at different sectors in the system

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the invention may be had from thefollowing description of a preferred embodiment, given by way of exampleand to be understood in conjunction with the accompanying drawingswherein:

FIG. 1 is a graphical representation of an SCH defined for 1.25 MHz;

FIG. 2 is a graphical representation of SCHs defined for 1.25 and 5 MHz;

FIG. 3 shows an exemplary wireless communication system, including abase station (BS) and a plurality of wireless transmit/receive units(WTRUs), configured in accordance with the present invention;

FIG. 4 is a functional block diagram of a WTRU and the BS of thewireless communication system of FIG. 3;

FIG. 5 is a flow diagram of a method for configuring secondarysynchronization channels (S-SCHs) of neighboring sectors multiplexed ina frequency division multiplexing (FDM) manner, in accordance with thepresent invention;

FIG. 6 is a flow diagram of a method for configuring S-SCHs ofneighboring sectors multiplexed in a code division multiplexing (CDM)manner, in accordance with the present invention;

FIG. 7 is an exemplary information field of an S-SCH, in accordance withthe present invention;

FIG. 8 is an exemplary diagram of a frame format with equal intervalsbetween primary SCH (P-SCH) symbols, in accordance with the presentinvention; and

FIG. 9 is an exemplary diagram of a frame format with unequal intervalsbetween P-SCH symbols, in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “base station” includes but isnot limited to a Node-B, a site controller, an access point (AP), or anyother type of interfacing device capable of operating in a wirelessenvironment.

The present invention is directed to a method and apparatus forsynchronization in an orthogonal frequency division multiple access(OFDMA) evolved universal terrestrial radio access (E-UTRA) system. Anew secondary synchronization channel (S-SCH) is configured and utilizedto perform synchronization. The S-SCH may achieve, among other things, ahigh cell search performance, a balanced peak to average power (PAPR)between the primary SCH (P-SCH) and the S-SCH, and a low computationcomplexity. The S-SCHs of different sectors may be multiplexed by, forexample, frequency division multiplexing (FDM) or code divisionmultiplexing (CDM).

FIG. 1 is a graphical representation of an SCH defined for 1.25 MHz. Asshown in FIG. 1, the SCH is centered in the middle of the availablebandwidth and is independent of the system bandwidth. FIG. 2 is agraphical representation of an SCH defined for 1.25 and 5 MHz. As shownin FIG. 2, the SCH is again centered in the middle of the availablebandwidth and is independent of the system bandwidth.

FIG. 3 shows an exemplary wireless communication system 100, including abase station (BS) 120 and a plurality of wireless transmit/receive units(WTRUs) 110, capable of wirelessly communicating with one another.Although the wireless communication devices depicted in the wirelesscommunication system 100 are shown as WTRUs and a base station, itshould be understood that any combination of wireless devices maycomprise the wireless communication system 100.

FIG. 4 is a functional block diagram of a WTRU 110 and the BS 120 of thewireless communication system 100 of FIG. 3. As shown in FIG. 4, theWTRU 110 and the BS 120 are in wireless communication with one another,and are configured to configure and utilize a secondary synchronizationchannel (S-SCH) in accordance with the present invention.

In addition to the components that may be found in a typical WTRU, theWTRU 110 includes a processor 115, a receiver 116, a transmitter 117,and an antenna 118. The processor 115 is configured to receive andprocess S-SCH symbols in accordance with the present invention. Thereceiver 116 and the transmitter 117 are in communication with theprocessor 115. The antenna 118 is in communication with both thereceiver 116 and the transmitter 117 to facilitate the transmission andreception of wireless data.

Similarly, in addition to the components that may be found in a typicalBS, the BS 120 includes a processor 125, a receiver 126, a transmitter127, and an antenna 128. The processor 125 is configured to generate andtransmit S-SCH symbols in accordance with the present invention. Thereceiver 126 and the transmitter 127 are in communication with theprocessor 125. The antenna 128 is in communication with both thereceiver 126 and the transmitter 127 to facilitate the transmission andreception of wireless data.

FIG. 5 is a flow diagram 500 of a method for configuring S-SCHs that aremultiplexed in an FDM manner in accordance with the present invention.In step 510, the S-SCH is generated to include cell-specificinformation.

The S-SCH symbols are then mapped to the central bandwidth, which may beperformed in a number of ways. The S-SCH symbols may be mapped to thecentral bandwidth regardless of the system transmission bandwidth (step520), or the S-SCH symbols may be mapped to the central bandwidthrespective of the system transmission bandwidth (step 525)

For example, referring back to FIG. 1, the S-SCHs are mapped to thecentral 1.25 MHz bandwidth regardless of the transmission bandwidth ofthe system (step 520). In this case, the S-SCHs will utilize the samenumber of subcarriers for all possible system bandwidths. Additionally,since the number of subcarriers is limited by the 1.25 MHz bandwidth,the number of subcarriers utilized should be relatively low, for exampleno more than 76 subcarriers.

Appropriate modulation and coding is then chosen to fit the amount ofcoded bits on the subcarriers utilized by the S-SCH (step 530). Inparticular, binary phase shift keying (BPSK) or quadrature phase shiftkeying (QPSK) should be used for modulation, and repetition coding orReed-Muller coding should be used to code the cell information bits.Table 1 below shows example parameters for an S-SCH in this case, wherethere is no tone reservation. TABLE 1 Transmission BW 1.25 MHz 2.5 MHz 5MHz 10 MHz 15 MHz 20 MHz IFFT size (N) 128 256 512 1024 1536 2048 Numberof 76 151 301 601 901 1201 available subcarriers Number of 75 75 75 7575 75 subcarriers that can be used for S-SCH Subcarriers 1, 4, 7, . . ., 73 1, 4, 7, . . . , 73 1, 4, 7, . . . , 73 1, 4, 7, . . . , 73 1, 4,7, . . . , 73 1, 4, 7, . . . , 73 used by S-SCH of sector 1 Subcarriers2, 5, 8, . . . , 74 1, 4, 7, . . . , 74 2, 5, 8, . . . , 74 2, 5, 8, . .. , 74 2, 5, 8, . . . , 74 2, 5, 8, . . . , 74 used by S-SCH of sector 2Subcarriers 3, 6, 9, . . . , 75 1, 4, 7, . . . , 75 3, 6, 9, . . . , 753, 6, 9, . . . , 75 3, 6, 9, . . . , 75 3, 6, 9, . . . , 75 used byS-SCH of sector 3

If tone reservation is required (step 540), the same number ofsubcarriers should also be utilized for tone reservation for allpossible system bandwidths (step 550). For example, 6 subcarriers may beused for tone reservation and 69 subcarriers used to transmit the S-SCHinformation. In this example, each sector uses 23 subcarriers totransmit its respective S-SCH information. Table 2 below shows exampleparameters for an S-SCH in this case, where there is tone reservation.TABLE 2 Transmission BW 1.25 MHz 2.5 MHz 5 MHz 10 MHz 15 MHz 20 MHz IFFTsize (N) 128 256 512 1024 1536 2048 Number of 76 151 301 601 901 1201available subcarriers Number of 75 75 75 75 75 75 subcarriers that canbe used for S-SCH Subcarriers 1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5, 6 1, 2, 3,4, 5, 6 1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5, 6 used for tonereservation Subcarriers 7, 10, . . . , 73 7, 10, . . . , 73 7, 10, . . ., 73 7, 10, . . . , 73 7, 10, . . . , 73 7, 10, . . . , 73 used by S-SCHof sector 1 Subcarriers 8, 11, . . . , 74 8, 11, . . . , 74 8, 11, . . ., 74 8, 11, . . . , 74 8, 11, . . . , 74 8, 11, . . . , 74 used by S-SCHof sector 2 Subcarriers 9, 12, . . . , 75 9, 12, . . . , 75 9, 12, . . ., 75 9, 12, . . . , 75 9, 12, . . . , 75 9, 12, . . . , 75 used by S-SCHof sector 3

In step 560, S-SCHs of different sectors are transmitted on differentsubcarriers. In this manner, collisions of S-SCHs may be avoided. Inaddition, equal-distant subcarriers may be used for the S-SCH persector, and the distance should be equal to the number of sectors. Forexample, a distance of three subcarriers would be used for a cell sitehaving three sectors.

In another example, referring back to FIG. 2, the S-SCH is mapped to thecentral 1.25 MHz and 5 MHz transmission bandwidths, respectively (step525). In this example, the S-SCH utilizes the different number ofsubcarriers correspondingly.

Appropriate modulation and coding is then chosen to fit the amount ofcoded bits utilized by the S-SCH (step 530). In the present example,since there are more subcarriers for the S-SCHs in the system withbandwidths no less than 5 MHz, more conservative coding and modulationschemes may be utilized. For example, cyclic redundancy check (CRC) orconvolutional coding may be used as compared to a system having abandwidth lower than 5 MHz.

Table 3 below shows example parameters for an S-SCH in this case, wherethere is no tone reservation. TABLE 3 Transmission BW 1.25 MHz 2.5 MHz 5MHz 10 MHz 15 MHz 20 MHz IFFT size (N) 128 256 512 1024 1536 2048 Numberof 76 151 301 601 901 1201 available subcarriers Number of 75 75 300 300300 300 subcarriers that can be used for S-SCH Subcarriers 1, 4, 7, . .. , 73 1, 4, 7, . . . , 73 1, 4, 7, . . . , 298 1, 4, 7, . . . , 298 1,4, 7, . . . , 298 1, 4, 7, . . . , 298 used by S-SCH of sector 1Subcarriers 2, 5, 8, . . . , 74 1, 4, 7, . . . , 74 2, 5, 8, . . . , 2992, 5, 8, . . . , 299 2, 5, 8, . . . , 299 2, 5, 8, . . . , 299 used byS-SCH of sector 2 Subcarriers 3, 6, 9, . . . , 75 1, 4, 7, . . . , 75 3,6, 9, . . . , 300 3, 6, 9, . . . , 300 3, 6, 9, . . . , 300 3, 6, 9, . .. , 300 used by S-SCH of sector 3

If tone reservation is required (step 540), a number of subcarriersshould also be utilized for tone reservation (step 550). For example,for S-SCHs utilizing 5 MHz, 24 subcarriers may be used for tonereservation and 276 subcarriers used to transmit the S-SCH information.In this example, each sector uses 92 subcarriers to transmit itsrespective S-SCH information. Table 4 below shows example parameters foran S-SCH in this case, where there is tone reservation. TABLE 4Transmission BW 1.25 MHz 2.5 MHz 5 MHz 10 MHz 15 MHz 20 MHz IFFT size(N) 128 256 512 1024 1536 2048 Number of 76 151 301 601 901 1201available subcarriers Number of 75 75 300 300 300 300 subcarriers thatcan be used for S-SCH Subcarriers 1, 2, 3, 4, 5, 6 1, 2, 3, 4, 5, 6 1,2, . . . , 24 1, 2, . . . , 24 1, 2, . . . , 24 1, 2, . . . , 24 usedfor tone reservation Subcarriers 7, 10, . . . , 73 7, 10, . . . , 73 25,28, . . . , 298 25, 28, . . . , 298 25, 28, . . . , 298 25, 28, . . . ,298 used by S-SCH of sector 1 Subcarriers 8, 11, . . . , 74 8, 11, . . ., 74 26, 29, . . . , 299 26, 29, . . . , 299 26, 29, . . . , 299 26, 29,. . . , 299 used by S-SCH of sector 2 Subcarriers 9, 12, . . . , 75 9,12, . . . , 75 27, 30, . . . , 300 27, 30, . . . , 300 27, 30, . . . ,300 27, 30, . . . , 300 used by S-SCH of sector 3

Regardless of any of the methods used above, if the number ofsubcarriers utilized by the S-SCH is less than the number of availablesubcarriers, the subcarriers not utilized by the S-SCH may be used forother purposes. For example, the unused subcarriers may contain otherdata or alternatively may be set to zero.

It should be noted that in tables 1, 2, 3, and 4 above, the subcarriersshown are exemplary. Other numerical subcarriers may be utilized inplace of, or in addition to, the subcarriers described in the abovetables.

FIG. 6 is a flow diagram of a method 600 for configuring S-SCHsmultiplexed in a code division multiplexing (CDM) manner, in accordancewith another embodiment of the present invention. The S-SCH symbol isgenerated in step 610. In the CDM case, all sectors utilize the samesubcarriers for the S-SCH (step 620). In addition, information bits aremapped across all subcarriers used by the S-SCH (step 630).

In order to reduce the PAPR of the S-SCH, polyphase codes or constantamplitude zero auto-correlation (CAZAC) codes should be used forspreading, and different sectors should use a different shift ofpolyphase codes to be orthogonal to one another (step 640). Amongpolyphase codes, GCL or Zadoff-Chu codes may be utilized.

For a particular length of N_(c), a generic polyphase code sequence maybe determined in accordance with the following equation: $\begin{matrix}{{G_{k} = {\mathbb{e}}^{{- j}\quad k^{2}\frac{\pi}{N_{c}}}},{k = 0},1,\ldots\quad,{N_{c} - 1.}} & {{Equation}\quad(1)}\end{matrix}$

Additionally, more orthogonal polyphase code sequences may be created byshifting the generic orthogonal polyphase sequence in phase.Accordingly, the lth shifted version of generic orthogonal polyphasesequence may be determined in accordance with the following equation:$\begin{matrix}{{G_{k}^{(l)} = {{\mathbb{e}}^{{- j}\quad k^{2}\frac{\pi}{N_{c}}} \cdot {\mathbb{e}}^{{- j}\quad k\quad l\frac{2\pi}{N_{c}}}}},{k = 0},1,\quad\ldots\quad,{N_{c} - 1},{l = 0},1,\ldots\quad,{N_{c} - 1.}} & {{Equation}\quad(2)}\end{matrix}$

Two polyphase code sequences with different shifts are substantiallyorthogonal to each other.

In step 650, the S-SCH symbol is mapped to the central part of thebandwidth. Additionally, subcarriers not used by the S-SCH may beutilized to contain other data or be set to a value of “zero.” In step660, the S-SCH is transmitted to WTRUs in the system.

In one example of the CDM method (600), when choosing N_(c) equal to 64,64 subcarriers would be used for the S-SCH. This would apply to a cellhaving a bandwidth less than 5 MHz only, such as shown in FIG. 2, or foran S-SCH in a cell such as shown in FIG. 1. If a spreading factor of 4is used, then 16 symbols may be transmitted on the S-SCH. If a spreadingfactor 8 is used, then 8 symbols may be transmitted on the S-SCH.

Again, depending on the number of bits contained in the S-SCH,appropriate modulation and coding is chosen to fit the amount of codedbits on the subcarriers used by the S-SCH. BPSK or QPSK should be usedfor modulation. Repetition coding or Reed-Muller coding may be used if asmall amount of uncoded bits are contained on the S-SCH.

In another example of the CDM method (600), when choosing N_(c) equal to256, 256 subcarriers would be used for the S-SCH. This also applies to acell having a bandwidth less than 5 MHz only, such as shown in FIG. 2,or for an S-SCH in a cell such as shown in FIG. 1. If a spreading factorof 8 is used, then 32 symbols may be transmitted on the S-SCH. Likewise,if a spreading factor of 16 is used, then 16 symbols may be transmittedon the S-SCH. However, if a spreading factor of 32 is used, then 8symbols may be transmitted on the S-SCH. Since more symbols may betransmitted in these schemes, more conservative coding (such asconvolutional coding) and modulation schemes may be used compared to asystem with a bandwidth lower than 5 MHz.

Several frame formats may be utilized, but in general, both a P-SCHsymbol and an S-SCH symbol should be transmitted one or more timesduring a single radio frame having a typical length of 10 milliseconds(ms). The number of transmitted P-SCH symbols and S-SCH symbols need notbe the same. However, the S-SCH symbols should be transmitted after theP-SCH symbols.

FIG. 7 is an exemplary information field 700 of an S-SCH, in accordancewith the present invention. Referring now to FIG. 7, the informationfield 700 includes a cell ID field 710, a number of transmit (TX)antennas field 720, a bandwidth field 730, and a reserved bits field740. It should be noted that any combination of these fields may bepresent, and that other fields not shown may also be included in theinformation field 700. The number of TX antennas field 720 typicallyincludes information relating to the number of TX antennas at a Node-Bin the system. The bandwidth field 730 includes information relating tothe bandwidth of the cell.

FIG. 8 is an exemplary diagram of a frame format 800 with equalintervals between P-SCH symbols, in accordance with the presentinvention. The frame format 800 includes a plurality of transmissiontime intervals (TTIs) 810 (designated as TTI 1, TTI 2, . . . , TTI 20).Each TTI 810 includes a plurality of OFDM symbols having a particularsymbol duration. As shown in FIG. 8, the first symbol of each oddnumbered TTI 810, (e.g., TTI 1, TTI 3, . . . ,TTI 19), includes a P-SCH820, such that equal intervals exist between P-SCH symbols. An S-SCH 830is included in TTI 19 following the P-SCH 820. It should be noted that,although the S-SCH 830 is depicted as immediately following the P-SCH820 in TTI 19, the S-SCH 830 could be transmitted at other timelocations relative to the P-SCH 820.

FIG. 9 is an exemplary diagram of a frame format 900 with unequalintervals between P-SCH symbols, in accordance with the presentinvention. The frame format 900 includes a plurality of transmissiontime intervals (TTIs) 910 (designated as TTI 1, TTI 2, . . . , TTI 20).Each TTI 910 includes a plurality of OFDM symbols having a particularsymbol duration. As shown in FIG. 9, a P-SCH symbol 920 is placed in thefirst symbol of particular TTIs 910, (e.g., TTI 2, TTI 5, TTI 9, TTI 14,and TTI 20). As shown in FIG. 9 unequal intervals exist between P-SCHsymbols. An S-SCH symbol 930 is placed in TTI 20 following the P-SCH 920and at the end of TTI 20. Likewise, a P-SCH symbol can be placed in thelast OFDM symbol of a TTI, and an S-SCH symbol may be placed in the OFDMsymbol before the P-SCH symbol. It should be noted that, although theS-SCH 930 is depicted as following the P-SCH 920 in TTI 20 at the end ofthe TTI, the S-SCH 930 could be transmitted at other time locationsrelative to the P-SCH 920.

The processors 125 of the BS 120 may be configured to perform the stepsof the methods 500 and 600 described above. The processors 115/125 mayalso utilize the receivers 116/126, transmitters 117/127, and antennas118/128, respectively, to facilitate wirelessly receiving andtransmitting data.

Although the features and elements of the present invention aredescribed in the preferred embodiments in particular combinations, eachfeature or element can be used alone without the other features andelements of the preferred embodiments or in various combinations with orwithout other features and elements of the present invention. Themethods or flow charts provided in the present invention may beimplemented in a computer program, software, or firmware tangiblyembodied in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) module.

1. A method for synchronization in an orthogonal frequency divisionmultiple access (OFDMA) evolved universal terrestrial radio access(E-UTRA) system including at least one base station and a plurality ofwireless transmit/receive units (WTRUs), the method comprising:centering a secondary synchronization channel (S-SCH) to the center ofan available bandwidth of the system; generating an S-SCH symbol toinclude cell-specific information; mapping the S-SCH symbol to thecenter of the available bandwidth of the system; and transmitting theS-SCH symbol on different subcarriers to the WTRUs in the system.
 2. Themethod of claim 1 wherein the S-SCH symbol includes any one of thefollowing data: the cell identifier (ID), a number of transmit antennasat a Node B, and the bandwidth of the cell.
 3. The method of claim 1,further comprising multiplexing S-SCHs of different sectors by frequencydivision multiplexing (FDM).
 4. The method of claim 3 wherein the S-SCHsymbol is mapped to the central bandwidth of the system independent ofthe system transmission bandwidth.
 5. The method of claim 4, furthercomprising selecting modulation and coding.
 6. The method of claim 5wherein the modulation and coding is selected based upon an amount ofcoded bits on subcarriers utilized by the S-SCH.
 7. The method of claim5 wherein the modulation is binary phase shift keying (BPSK) orquadrature phase shift keying (QPSK).
 8. The method of claim 5 whereinthe coding is repetition coding or Reed-Muller coding.
 9. The method ofclaim 4 wherein the S-SCH utilizes the same number of subcarriers forall bandwidths within the system.
 10. The method of claim 3, furthercomprising mapping the S-SCH to the central bandwidth of the systemrespective of the system transmission bandwidth.
 11. The method of claim10, further comprising employing cyclic redundancy check (CRC) orconvolutional coding.
 12. The method of claim 3 wherein the S-SCHutilizes a different number of subcarriers corresponding to thebandwidths within the system.
 13. The method of claim 1 wherein thenumber of subcarriers utilized by the S-SCH is less than the number ofavailable subcarriers.
 14. The method of claim 13, further comprisingsetting subcarriers not utilized by the S-SCH to zero.
 15. The method ofclaim 13, further comprising including data in the subcarriers notutilized by the S-SCH.
 16. The method of claim 1, further comprisingreserving a number of subcarriers for tone reservation.
 17. The methodof claim 1 wherein the subcarriers used for the S-SCH are equal indistance.
 18. The method of claim 17 wherein the distance is equal tothe number of sectors.
 19. The method of claim 1, further comprisingmultiplexing S-SCHs of different sectors by code division multiplexing(CDM).
 20. The method of claim 20 wherein sectors utilize the samesubcarriers for the S-SCH.
 21. The method of claim 20, furthercomprising spreading information bits across the subcarriers utilized bythe S-SCH.
 22. The method of claim 21 wherein the spreading includespolyphase codes.
 23. The method of claim 22 wherein different sectorsutilize a different shift of polyphase codes.
 24. The method of claim 23wherein the polyphase codes are orthogonal to one another.
 25. Themethod of claim 1, further comprising transmitting a primarysynchronization channel (P-SCH) symbol at least once during a singleradio frame.
 26. The method of claim 25, further comprising transmittingan S-SCH symbol at least once during a single radio frame.
 27. Themethod of claim 26 wherein the S-SCH symbols are transmitted after theP-SCH symbols.
 28. The method of claim 26 wherein the number oftransmitted P-SCH symbols differs from the number of transmitted S-SCHsymbols.
 29. The method of claim 25 wherein an equal interval existsbetween P-SCH symbols.
 30. The method of claim 25 wherein an unequalinterval exists between P-SCH symbols.
 31. In an orthogonal frequencydivision multiple access (OFDMA) evolved universal terrestrial radioaccess (E-UTRA) system including at least one base station and aplurality of wireless transmit/receive units (WTRUs), the base stationincluding: a receiver; a transmitter; and a processor in communicationwith the receiver and the transmitter, the processor configured tocenter a secondary synchronization channel (S-SCH) to the center of anavailable bandwidth of the system, generate an S-SCH symbol to includecell-specific information, map the S-SCH symbol to the center of theavailable bandwidth of the system, and control the transmitter totransmit the S-SCH symbol on different subcarriers to the WTRUs in thesystem.
 32. The base station of claim 32 wherein the processor isfurther configured to multiplex the S-SCHs using frequency divisionmultiplexing (FDM).
 33. The base station of claim 32 wherein theprocessor is further configured to multiplex the S-SCHs using codedivision multiplexing (CDM).
 34. The base station of claim 32 whereinthe processor is further configured to modulate the transmission usingany one of the following modulation schemes: binary phase shift keying(BPSK) and quadrature phase shift keying (QPSK).
 35. The base station ofclaim 32 wherein the processor is further configured to code thetransmission using any one of the following coding: repetition coding,Reed-Muller coding, cyclic redundancy check (CRC), and convolutionalcoding.
 36. The base station of claim 32 wherein the processor isfurther configured to spread information bits across subcarriersutilized by the S-SCH.
 37. In an orthogonal frequency division multipleaccess (OFDMA) evolved universal terrestrial radio access (E-UTRA)system including at least one base station and a plurality of wirelesstransmit/receive units (WTRUs), the base station including an integratedcircuit (IC), the IC comprising: a receiver; a transmitter; and aprocessor in communication with the receiver and the transmitter, theprocessor configured to center a secondary synchronization channel(S-SCH) to the center of an available bandwidth of the system, generatean S-SCH symbol to include cell-specific information, map the S-SCHsymbol to the center of the available bandwidth of the system, andcontrol the transmitter to transmit the S-SCH symbol on differentsubcarriers to the WTRUs in the system.
 38. The IC of claim 37 whereinthe processor is further configured to multiplex the S-SCHs usingfrequency division multiplexing (FDM).
 39. The IC of claim 37 whereinthe processor is further configured to multiplex the S-SCHs using codedivision multiplexing (CDM).
 40. The IC of claim 37 wherein theprocessor is further configured to modulate the transmission using anyone of the following modulation schemes: binary phase shift keying(BPSK) and quadrature phase shift keying (QPSK).
 41. The IC of claim 37wherein the processor is further configured to code the transmissionusing any one of the following coding: repetition coding, Reed-Mullercoding, cyclic redundancy check (CRC), and convolutional coding.
 42. TheIC of claim 37 wherein the processor is further configured to spreadinformation bits across subcarriers utilized by the S-SCH.